Because the image is a composite, only part of the robot's arm is visible -- although you can see its shadow. And if you look really closely, you might even spot what looks like an emoji in the drilling pattern:

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NASA/JPL-Caltech/MSSS

Who said space robots don't have a sense of humor?

NASA also released a stereographic projection, in which the horizon is turned into a circle -- making it seem as if the rover is sitting atop a tiny planet of its own:

NASA/JPL-Caltech/MSSS

NASA said the site was chosen for drilling because the rock in the area is unusually high in silica and hydrogen.

The hydrogen is a sign of water bound to minerals in the ground, the agency said on its website.